Major karyotypic abnormalities in a near-tetraploid erythroleukemia.

A case of erythroleukemia (EL; FAB M6) is presented in which the leukemic cells of the marrow were characterized by two ranges in the chromosome number, i.e., one hypodiploid and another near-tetraploid. All characteristics of major karyotypic abnormalities (MAKA) were present, i.e., increased karyotype instability with variation of the chromosome count from metaphase to metaphase, dicentrics, acentrics, marker chromosomes, double minute chromosomes (DMs), and centromere spreading. All of these events were variably represented from metaphase to metaphase. The prognosis was poor, with survival of 1 month after the diagnosis of EL. The meaning of extreme MAKA in the classification of EL is discussed.